Bacterial overgrowth is a condition found primarily in the elderly and is estimated to affect 33% of people over 65 years. It causes great discomfort and clinically important nutritional deficiencies if left untreated. The underlying cause is reduced gastric acid secretion associated with aging. Management of overgrowth is hampered because low cost and easy to use diagnostic tests do not exist. Detection is meaningful because while the condition is never cured it can be effectively controlled through treatment. Our objective is to develop an easy to use and cost effective test to detect bacterial overgrowth. The clinical utility is the ability to detect the bacteria overgrowth as accurately as the gold standard (jejunal cultures) in patients exhibiting classic disease symptoms but whom ordinarily wouldn't receive expensive and invasive jejunal culture. The test will accurately detect the condition pre- and post-therapy and lead to quality of life improvement. The novelty of this proposal is the use of a non-invasive breath test employing a naturally occurring sugar labeled with carbon-13 as a probe. If overgrowth is present, the bacteria is present, the bacteria in the small intestine metabolize the labeled substrate and high concentrations of (13)CO(2) are expired in the breath. PROPOSED COMMERCIAL APPLICATION: There are 25 million Americans over the age of 65 and they accounted for 10 million physician office visits with complaints of classic overgrowth symptoms The proposed test will significantly reduce national health care expenditures because proper diagnosis will lead to fewer office visits, more prudent use of drugs and better general health and well-being in the elderly.